October 2017

Very central epithelial basement membrane dystrophy (EBMD) that causes irregular astigmatism, which could be misinterpreted as ectasia, without the proper clinical exam and correlation; repeat topography and cataract surgery diagnostics were performed 6 weeks after the superficial
keratectomy, which demonstrates much more regular astigmatism, with a drastically reduced
magnitude and average keratometric value
Source: Elizabeth Yeu, MD

Ensuring optimal health of the cornea before cataract surgery will help surgeons create the best possible outcome for patients.
Seasoned cataract surgeons use a number of preop assessments and treatments to evaluate and improve corneal health—and sometimes, those treatments must extend postoperatively. The goal with the preop and postop treatments is to offer great quality of vision.
One important starting point when assessing corneal health is the patient history, said Elizabeth Yeu, MD, Virginia Eye Consultants, Norfolk, Virginia. She will inquire about things like corneal pain upon awakening, recurrent erosions, and fluctuations in vision. She also likes to ask about glare symptoms at night. “Corneal guttata can lead to glare disproportionate to cataract,” Dr. Yeu said. If she evaluates a patient with early nuclear changes but significant guttata, she knows she will need to manage both the cornea and cataract.
Assessment for ocular surface disease before cataract surgery is important, said Shahzad Mian, MD, Terry J. Bergstrom Collegiate Professor for Resident Education in Ophthalmology and Visual Sciences, University of Michigan, Ann Arbor. Tests that he will use include tear breakup time, fluorescein staining, and lissamine green staining. “Many patients in the age group for cataract surgery have dry eye disease, and it’s associated with increased tear evaporation caused by lid disease,” he said.
Sometimes Dr. Mian will obtain a Schirmer’s score, which can potentially indicate low aqueous tear dysfunction.
“I also look for other causes of surface irregularity. Some are subtle, and some are easy to see,” he said. This includes searching for signs of anterior basement membrane dystrophy, which can be identified carefully with a narrow slit beam, Salzmann’s nodules, corneal scarring from previous trauma, and limbal conditions such as pterygium or pseudopterygium. “With those, it’s very helpful to perform corneal imaging such as topography to see the impact on the cornea curvature,” Dr. Mian said.
One finding Dr. Yeu evaluates is Placido disk imaging, which she uses as part of her astigmatism evaluation. “If the Placido disk image is poor, I know I can’t take what I’m seeing as a true astigmatism,” she said.
Drs. Yeu and Mian do not always perform specular microscopy, but it can sometimes provide information on lens density.
“For academic interest, we will also do specular microscopy for endothelial cell counts and corneal thickness, but this does not replace a good history inquiring about morning blurring that improves after some time and a clinical exam for corneal edema,” said Clara Chan, MD, assistant professor, University of Toronto.
Meibography and tear osmolarity tests can provide concrete information for some patients who may need to clear up their ocular surface before cataract surgery, especially if they want a refractive cataract option, Dr. Yeu said.

Preop treatments for the cornea

Cataract surgeons will start a variety of treatments with the goal of helping the ocular surface before surgery. For Dr. Chan, this can include lubrication, topical steroids, omega-3 fatty acids, topical cyclosporine (Restasis, Allergan, Dublin, Ireland), and warm compresses and lid hygiene scrubs twice daily. “In more severe cases, we may need to use doxycycline if facial rosacea is present,” Dr. Chan said.
One component of treatment is preparing patients to potentially continue certain therapies after surgery as well. “Patients have to understand that if they’re not already on therapy, they will have to commit to being on some form of therapy, including nutraceuticals,” Dr. Yeu said. “If they’re not willing to do that, you may still have an unhappy patient [postoperatively]. That conversation needs to be had, especially if the patient is looking for spectacle independence.”
Newer treatments available within the office such as LipiFlow (TearScience, Morrisville, North Carolina), BlephEx (Franklin, Tennessee), and intense pulsed light can also be used, Dr. Mian said.
He finds out if patients have a history of herpetic keratitis, which could flare again after cataract surgery. In these patients, he will manage with anti-viral medications before and after surgery.
Dr. Yeu realizes how eager patients are to get their cataract surgery done, so while turnaround for surgery is usually 3 to 4 weeks, she will typically push the surgical schedule 6 to 8 weeks out for patients with ocular surface disease with corneal staining. She will see such patients in 3 weeks for a follow-up appointment with repeat cataract diagnostics preoperatively. If they’re not quite ready for surgery, she’ll use the extra time for corneal treatments and may stretch out surgery for the second eye to provide a bit more time for ocular surface treatment and recovery.
However, patients with moderate to severe disease often require even more time before cataract surgery. One resource Dr. Yeu has found helpful is self-retaining amniotic membrane therapy. It can be uncomfortable for a patient for 3 to 4 days, but it helps improve the corneal surface rapidly, allowing for more accurate diagnostic imaging, she said.

Corneal, cataract surgery timing

If a patient requires endothelial keratoplasty and cataract surgery, surgeons carefully weigh how to time the procedures. “For a surgeon just starting out with Descemet’s membrane endothelial keratoplasty [DMEK] or Descemet’s stripping endothelial keratoplasty [DSEK], staging the phaco first is helpful so that when the corneal graft is being done, that’s all the surgeon has to focus on,” Dr. Chan said. “In DMEK, it is helpful for the pupil to be constricted, and if done in combination with phaco, where the pupil has to be dilated, it can make the DMEK more challenging.”
However, if a patient has morning blur complaints and known Fuchs’ dystrophy with cataract, she recommends a combination surgery. Dr. Yeu agreed. “The more that they’re having clinical signs of corneal edema, the more likely it is I’ll do a combined procedure versus cataract surgery alone,” Dr. Yeu said.
“If it’s a gradual decline in vision, and corneal disease is not as severe based on the clinical exam, I lean toward cataract surgery only,” Dr. Mian said. “This is where [obtaining] endothelial cell density may be helpful.”
If corneal endothelial disease is less severe, Dr. Mian prefers to perform DMEK; in advanced cases with moderate to severe edema or scarring, his choice is DSEK.
Although there has been a lot of buzz about femtosecond laser-assisted cataract surgery (FLACS), its advantages are not necessarily as valuable in patients with concurrent endothelial disease.
“It could minimize ultrasound energy use, but it depends on the density of the lens,” Dr. Mian said. “Femtosecond phaco is not covered by any insurance, so cost becomes a factor. I do use a dispersive viscoelastic to protect the endothelium.”
If a patient has some endothelial dysfunction but can have cataract surgery alone, Dr. Yeu will use FLACS. However, if combining cataract surgery with an EK, she will use manual cataract surgery.
Dr. Chan also sees the advantage of using less phaco energy to emulsify a cataract, especially a dense one, thereby helping to preserve the corneal endothelium. However, “Femto wounds can cause more endothelial apoptosis, so I would not use the femto laser to create incisions in patients with a compromised corneal endothelium,” she said.

Editors’ note: The physicians have no financial interests related to their comments.